Ternary composite amendments of sludge-humic acid-fertilizer for mineral mud paddy field utilization

To address severe challenges posed by the contamination of mineral mud, a ternary composite comprising sludge, humic acid, and silica-calcium-magnesium (Si-Ca-Mg) fertilizer was developed. The system aims to achieve multi-dimensional paddy field utilization through synergistic mechanisms with mining mud. Field experiment results demonstrated that the amended mineral mud exhibited a pH increase of 9.46%-13.07% and significant improvements in nutrition, thus showing higher rice yields compared with the control group. The amendments promoted soil particle aggregation; consequently, heavy metals in the mineral mud tended to be in-situ deposited, rather than being taken up by plants, which also confirmed the reduction of the health risk assessment. Microbial community analysis revealed that the composite amendments significantly influenced the diversity of sludge microbial communities. The findings provide a theoretical foundation for the remediation of mineral mud and the ecological restoration of mining areas.